I think that the welds check for L-shape welded gusset is all way wrong. Please see attached robot file.
The welds shall be disposed on boths sides of the gusset.
The welds shall be designed as an L-shape geometrical figure, please see "Konstrukcje spawane" K and J Ferenc, see attached scereenshot.
Please could you cast your eye on it as this type of connection is one of the most important.